1. Field of the Invention
The invention relates to a channel setting method and a receiving apparatus which are suitable for use in a system to broadcast and distribute music by a digital satellite broadcasting.
2. Description of the Related Art
The digital satellite broadcasting is being spread. The digital satellite broadcasting is resistant to noises or fading and can transmit a signal of a high quality as compared with the existing analog broadcasting. As frequency use efficiency is improved multiple channels can be realized. For example, in the digital satellite broadcasting, hundreds of channels can be assured by one satellite. In such a digital satellite broadcasting, a number of dedicated channels for sports, movie, music, news, etc. are prepared. In the dedicated channels, a program having an exclusive-use content is broadcasted.
The music channel among the dedicated channels is one of the popular channels and a program for promotion to mainly introduce a new music piece or a hit music piece or the like is broadcast.
In the conventional music channel, as mentioned above, a program of an introduction of a new music piece or a hit music piece is sent by a motion image and an audio sound. There is a case where a viewer looks at such a music channel and if there is a favorite music piece, he wants to purchase a CD (Compact Disc) or the like of the introduced music piece and enjoy it. There is also a case where the viewer wants to know information of an artist of the music piece or information of an album in which such a music piece has been recorded. When the viewer watches a music program and if he wants to know the information of the artist of the music piece or the information of the album in which the music piece has been recorded, the information can be obtained right there. When there is a favorite music piece, if audio data of the music piece can be downloaded, it is very convenient. In the conventional music channel, however, a motion image and an audio sound regarding the music piece are unilaterally sent and such a request cannot be satisfied.
To solve the above problem, therefore, a music contents distributing system which can easily obtain information regarding music which is being broadcasted in a music channel and can easily download its music data into a data storing apparatus has been proposed.
In such a music contents distributing system, a main music program is broadcasted in one channel and data of a music piece to be downloaded is broadcasted in another channel. For example, when there is data of ten music pieces for downloading, one channel serving as a main channel and ten channels for downloading are used. In case of using the music contents distributing system, the channel of the main music program is first selected. When a music piece is designated in the main music program, the channel is switched to the channel corresponding to the designated music piece.
As mentioned above, the music contents distributing system comprises a channel of the main music program and a plurality of channels for downloading music data and it is desired that those channels are associated with each other. Since the music data is downloaded every music piece, it is desired that the accounting can be set every channel for downloading.
The channel setting of the conventional digital satellite broadcasting is performed by using PSI (Program Specific Information) including: an NIT (Network Information Table) in which information regarding a whole network has been described; a PAT (Program Association Table) in which information regarding streams of the same carrier wave has been described; and a PMT (Program Map Table) in which a PID (Packet Identifier) of a packet of a component (video/audio or the like) constructing a program of each channel number has been described. In such a conventional station selecting method, since each channel is individually independently set, a plurality of channels cannot be set in association with one another.
If a plurality of programs can be set in association with one another, it is desirable that an accounting system is changed every program or the program can be independently edited.
It is, therefore, an object of the invention to provide a channel setting method and a receiving apparatus in which a plurality of channels can be set in association with one another, an accounting system can be changed every channel, and a program can be drawn up.
According to the invention, there is provided a channel information transmitting method of a digital TV broadcasting for broadcasting a main channel comprising a video image and an audio signal and subchannels associated with the main channel, comprising the steps of: transmitting a first program map table in which information regarding a video component and an audio component of the main channel has been described; transmitting a second program map table in which information regarding components of the subchannels has been described; and describing the information of the second program map table into the first program map table and transmitting it.
According to the invention, there is provided a receiving apparatus for receiving a digital TV broadcasting for broadcasting a main channel comprising a video image and an audio signal and subchannels associated with the main channel, comprising: first extracting means for extracting a first program map table in which information regarding a video component and an audio component of the main channel included in the digital TV broadcasting signal has been described; obtaining means for obtaining information of a second program map table described in the extracted first program map table; and second extracting means for extracting the second program map table in which information regarding components of the subchannels included in a digital TV broadcasting signal has been described on the basis of the obtained information of the second program map table.
According to the invention, only information of the PMT of a program number of the main channel is described in the PAT as an information table of the PMT of a set carrier frequency. When there are subchannels associated with the main program, the information of the PMT of the program numbers of the subchannels is described in the PMT. Thus, the main channel which can be set from the PAT and the subchannels which are set from the PMT of the main channel can be set.
Since the main channel and the subchannels are set by using the PMTs of a similar format, there is no need to modify the existing system. The subchannels are channels similar to the main channel and can be independently set in each channel with respect to the scrambling and charging.
The above and other objects and features of the present invention will become apparent from the following detailed description and the appended claims with reference to the accompanying drawings.